The Police Federation of Northern Ireland condemned those behind two nights' violent disorder in north Belfast, during which more than 60 police officers were injured. At least three police officers had to be hospitalised.

Terry Spence, the federation's chairman, said of the officers on the front line in the Carlisle Circus/Lower Shankill area: "Their bravery and courage is in stark contrast to that of the cowardly thugs responsible for trying to murder them."

Fifteen police officers were injured in Monday night's disturbances when the Police Service of Northern Ireland fired up to six plastic baton rounds and deployed water cannon to quell trouble from up to 300 loyalists who had gathered in the area following a teatime protest.

North Belfast Assembly member Alban Maginness of the nationalist SDLP claimed there was "nothing spontaneous" about the rioting.

"The bulk of the violence over the past two days has, I believe, been sustained by loyalist paramilitaries. I think this is an attempt to intimidate the lawful authorities," he said.

Loyalist sources told the Guardian the Ulster Volunteer Force and members of the Ulster Defence Association were involved in the trouble on both nights.

Hijacked vehicles were set alight and in some cases were driven into police lines while motorists were advised to stay away from the area.

As on Sunday night, loyalists near the Lower Shankill estate bombarded police officers with up to 15 petrol bombs, fireworks, bottles and bricks.

The violence at the weekend followed a parade by a republican flute band passing by nearby Clifton Street Orange Hall. Up to 47 officers were injured in 10 hours of disorder that lasted into the early hours of Monday morning.